Functions of suppress-time on S series switches

For an S series switch, to protect an upstream Layer 3 device from attacks and reduce the loads on the Layer 3 device, a Layer 2 device can suppress repeated IGMP Report and IGMP Leave messages sent from users in a VLAN. The message suppression mechanism is as follows:

- After receiving and forwarding an IGMP Report/Leave message, the Layer 2 device does not forward repeated MLD Report messages to the router port within the suppression time.
- If the Layer 2 device receives an IGMP General Query message or Multicast-Address-Specific message within the suppression time, it does not suppress the first IGMP Report message sent in response to the General Query message. In addition, the Layer 2 device resets the suppression timer when receiving the first IGMP Report message.

suppress-time is used to set the suppression time of Report/Leave messages. By default, the suppression time for IGMP Report/Leave messages is 10s. If the suppression time is set to 0, Report/Leave messages are not discarded. The suppression function applies only to IGMPv1 and IGMPv2 Report/Leave messages and is invalid for IGMPv3 Report/Leave messages.

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